filer prefer volume server in same data center (#3405)

* initial prefer same data center
https://github.com/seaweedfs/seaweedfs/issues/3404

* GetDataCenter

* prefer same data center for ReplicationSource

* GetDataCenterId

* remove glog

weed/s3api/s3api_server.go

@@ -29,6 +29,7 @@ type S3ApiServerOption struct {
 	AllowEmptyFolder          bool
 	AllowDeleteBucketNotEmpty bool
 	LocalFilerSocket          *string
+	DataCenter                string
 }
 
 type S3ApiServer struct {